Identification notes
Tutors of bryophyte courses sometimes like to call this large acrocarp the ‘chocolate and lime’ moss to help tutees remember it. Indeed, this does describe the colour of A. palustre very nicely – its yellow-green leaves contrasting with the rich brown colour of the dense felt of rhizoids on the lower stem.
When seen growing as robust shoots in a deep cushion in moorland, mires or other wet organic habitats, often alongside common species of Sphagnum, there’s usually no mistaking it. Just occasionally, though, it has striking, lollipop-like gemmiferous shoots and then it resembles its smaller relative, A. androgynum, a species of drier places such as decaying stumps in woodland.
Helpfully, A. palustre is as striking under the compound microscope as it is in the field. Mid-leaf it has small, rounded-angular cells with thick walls, each one bearing a single mamilla (conical protuberance). There is little else that looks like that!
Read the Field Guide account